My engine is boring...

workaholic_ro · 31st March 2009, 16:41

...and decided this afternoon to show a new face of its personality. Started to alternate the idle revs from 950 to 600 and back, not randomly but with mathematical precision, like a swiss watch.
This engine has new cambelts and all related stuff, new thermostat, new NGK spark plugs; the purge and IAC valves are working; the VIS valves actuators are periodically removed, dismantled, cleaned and inspected and obviously in perfect condition; no hose, pipe or connection is out of it's place; ECU is not swimming; no air leaks; new filters, oil and coolant; aparently nothing was wrong.
So what, if it decided to show me new tricks ? I waited more than 5 minutes to see if something is changing, than pushed it up to 7000 rpm and back to idle...but THAT idle again.

After resetting the system the idle came back to its normal 650; I know it's about 150-200 lower than the recommended value but it has never been different so I don't bother.
I can't even blame Bill Gates, my ECU is running under Linux

Obviously, we will never know were was the hook in the software, I just want to advise you, if something similar ever happens don't start by removing the crankshaft or the gearbox.

Try the 13mm wrench first.

stocktake · 31st March 2009, 16:56

Mine does this now and again, either a quick blip on the throttle or ign off and back on again sorts it. Dash rev counter on mine shows around 6000rpm but when hooked up to an obd2 scanware program shows 750rpm ish. Dash RPM is gererally shown as low for some reason.

amableson · 31st March 2009, 17:55

I was told by a mgr mechanic some time ago that if you don't turn on the ignition and wait for a couple of seconds before you start the car the electronics will not stabalize and can cause uneven running and tickover. Have no idea if it's right but in electronics makes sense and i do it myself, Turn on ignition wait a bit and then start.

workaholic_ro · 31st March 2009, 18:02

Quote:

Originally Posted by amableson

Have no idea if it's right but in electronics makes sense and i do it myself, Turn on ignition wait a bit and then start.

It must be for the glow plugs

(sorry, couldn't resist)
Yes, it makes sense, this will give time to the ECU to load all the required ".dll"s and "activeX" files.

No more jokes, good advice!

amableson · 31st March 2009, 19:23

Gives the hamster time to 'run' up to speed.

StevenWilliams · 31st March 2009, 19:38

I've heard that if the alternator is on the way out it can cause this.

workaholic_ro · 31st March 2009, 19:43

Quote:

Originally Posted by StevenWilliams

I've heard that if the alternator is on the way out it can cause this.

mossey · 1st April 2009, 09:47

I had a similar problem to this when I lived in america, my 4.0l explorer used to hunt on idle which I traced to a TPS (throttle position sensor) it was a little dirty and needed replacing.
Don't know if this will help but I thought it would be worth a mention.
Good luck.

Lates · 1st April 2009, 11:30

Any fault codes, has the problem started since other works ?

workaholic_ro · 1st April 2009, 15:00

Quote:

Originally Posted by Lates

Any fault codes, has the problem started since other works ?

Not in my case. Nothing special happened, no repairs or maintenance operations lately. No idea about any fault codes, I didn't test it. I still suspect a "Bill Gates related problem".

31st March 2009, 16:41	#1
workaholic_ro Gets stuck in Rover 75 Saloon Join Date: Mar 2007 Location: Cluj Posts: 551 Thanks: 0 Thanked 3 Times in 3 Posts	My engine is boring... ...and decided this afternoon to show a new face of its personality. Started to alternate the idle revs from 950 to 600 and back, not randomly but with mathematical precision, like a swiss watch. This engine has new cambelts and all related stuff, new thermostat, new NGK spark plugs; the purge and IAC valves are working; the VIS valves actuators are periodically removed, dismantled, cleaned and inspected and obviously in perfect condition; no hose, pipe or connection is out of it's place; ECU is not swimming; no air leaks; new filters, oil and coolant; aparently nothing was wrong. So what, if it decided to show me new tricks ? I waited more than 5 minutes to see if something is changing, than pushed it up to 7000 rpm and back to idle...but THAT idle again. After resetting the system the idle came back to its normal 650; I know it's about 150-200 lower than the recommended value but it has never been different so I don't bother. I can't even blame Bill Gates, my ECU is running under Linux Obviously, we will never know were was the hook in the software, I just want to advise you, if something similar ever happens don't start by removing the crankshaft or the gearbox. Try the 13mm wrench first. __________________ Renee Descartes walks into a bar, the bartender says 'sir can I get you a martini 'Descartes says 'I don't think...' and he disappears Cheers, Fidel

31st March 2009, 16:56	#2
stocktake Vis Whiz Rover 75 2.5 auto Saloon Join Date: Jun 2007 Location: LEEDS Posts: 20,591 Thanks: 2,057 Thanked 3,056 Times in 1,621 Posts	Mine does this now and again, either a quick blip on the throttle or ign off and back on again sorts it. Dash rev counter on mine shows around 6000rpm but when hooked up to an obd2 scanware program shows 750rpm ish. Dash RPM is gererally shown as low for some reason. __________________ Dave... Lost a few stones and a Gall Bladder and part of a bile duct and all of my dignity in the suppository incident

31st March 2009, 17:55	#3
amableson Gets stuck in Ex Rover 75 owner Join Date: Nov 2006 Location: Boston, Lincolnshire. Posts: 553 Thanks: 0 Thanked 2 Times in 2 Posts	I was told by a mgr mechanic some time ago that if you don't turn on the ignition and wait for a couple of seconds before you start the car the electronics will not stabalize and can cause uneven running and tickover. Have no idea if it's right but in electronics makes sense and i do it myself, Turn on ignition wait a bit and then start. __________________ Regards Andrew.[SIGPIC][/SIGPIC]

31st March 2009, 19:23	#5
amableson Gets stuck in Ex Rover 75 owner Join Date: Nov 2006 Location: Boston, Lincolnshire. Posts: 553 Thanks: 0 Thanked 2 Times in 2 Posts	Gives the hamster time to 'run' up to speed. __________________ Regards Andrew.[SIGPIC][/SIGPIC]

31st March 2009, 19:38	#6
StevenWilliams This is my second home Rover 75 Saloon 2.5 V6 British Racing Green. 81,000 miles and counting Join Date: Apr 2008 Location: Crawley, West Sussex Posts: 6,183 Thanks: 0 Thanked 2 Times in 2 Posts	I've heard that if the alternator is on the way out it can cause this. __________________ [SIGPIC][/SIGPIC] Rover 75 2.5 2000 Club SE. British Racing Green. MEMBER NUMBER: MMMDCCXXVI Looking for: 7 seater

1st April 2009, 09:47	#8
mossey Regular poster Rover 75 tourer cdt Join Date: Nov 2008 Location: sheffield Posts: 89 Thanks: 0 Thanked 0 Times in 0 Posts	I had a similar problem to this when I lived in america, my 4.0l explorer used to hunt on idle which I traced to a TPS (throttle position sensor) it was a little dirty and needed replacing. Don't know if this will help but I thought it would be worth a mention. Good luck.

1st April 2009, 11:30	#9
Lates This is my second home Jaguar XE Join Date: Nov 2006 Location: Coventry Posts: 4,321 Thanks: 56 Thanked 59 Times in 55 Posts	Any fault codes, has the problem started since other works ?